Critic training.    
We use the conservative target in the offline RL literature [1]}, [2]}:
\( \textstyle \leavevmode \xbox {resizebox}{\XMLaddatt {width}{397.10687pt}\widetilde{Q}\left(s, a\right) \triangleq r(s,a) + \gamma \mathbb {E}_{a^{\prime }\sim \pi _{{\mathbf {\phi }}^{\prime }}\left(\cdot \,|\,s^{\prime }\right)}[c \min _{j=1,2}Q_{{\mathbf {\theta }}^{\prime }_j}\left(s^{\prime }, a^{\prime }\right) + (1-c) \max _{j=1,2}Q_{{\mathbf {\theta }}^{\prime }_j}\left(s^{\prime }, a^{\prime }\right)]\,,}\) 
